Choosing the right tyres

It’s no surprise that car tyres have poorer grip on a wet road than a dry one, but you might be surprised at how big a difference there can be between one set of tyres and another. Our tests show that most tyres perform well on dry roads – but on a wet surface, it’s a different story.

Compared to the two top performers, the worst-performing tyre in the wet took an extra 4m to stop at 50km/h and up to an extra 10m to stop at 80km/h.

In an emergency stop, that 10m distance could be the difference between pulling up a couple of car lengths short of the car in front and a trip to the auto repairer – or maybe the hospital.

Our test results aim to give you this essential performance information. We look at 15 models of size 205/60R16, suitable for at least some versions of popular current and older-model medium-sized cars such as the Holden Cruze (test car), Ford Focus and Mitsubishi Lancer.

According to the Australian Vehicle Standard, it is mandatory for all tyres to be stamped with the date of manufacture. You will find either a three- or four-digit code on either side of the tyre sidewall. Three digits are used on tyres made before 2000, and the first two digits stand for the week in the year and the last digit stands for the year. So a three-digit number of 078 stands for the seventh week in 1998. Four-digits are used on tyres made after 2000, and the first two digits stand for the week in the year, while the last two digits stand for the year. So a four-digit number of 0209 stands for the second week in 2009.

Although there is no recommended time period in the standard regarding how long before you replace your tyres, we often see retailers recommending five to six years for the replacement period. Tyre ageing depends on the many variables of how it is used.

Thingsto consider when purchasing a tyre include the signs of age, such as micro splits in the tyre tread and sidewall that are visible up close, which is aresult of oxidation of the tyre.

Each tyre has standard markings that allow you to pick the right type for your car. It’s a confusing mix of letters and numbers, and of measurements in mm and inches. Using the code for the tested size, P 205/60 R16 V and H, here’s what it all means:

P Passenger tyre.

205 The section width (in mm), which is the distance between the tyre's exterior sidewalls when the tyre is fitted to the recommended rim, inflated to the recommended pressure, and not under load.

60 The percentage, which describes the tyre’s profile or aspect ratio. It’s the ratio between the tyre’s section height (distance from the wheel bead seat to the top of the tyre) and its section width — in this case 60%.

R Radial, which is the most common construction method for passenger car tyres.

Our cornering tests are carried out with the car’s traction control disabled. CHOICE does not recommend disabling traction control as it aids the car’s handling and safety in extreme circumstances.

Cornering: Our testers, Peter Horvath and Chris Barnes, assess how well the tyres keep the car in a set lane at speeds of 80km/h and 85km/h in dry conditions, and of 70kmh, 75km/h and 80km/h in wet conditions, using a right-hand corner with about a 55m radius. The driver doesn’t know which brand of tyre has been fitted, and the tyres are tested in random order. The testers repeat the cornering test on a different day and in different random order.

Braking: Using a GPS system, our testers measure the distance it takes to come to a complete standstill in emergency braking tests from driving speeds of 50km/h and 80km/h in both dry and wet conditions.

Rolling noise: Our testers also carry out rolling noise measurements at the driver’s left ear at 50km/h and 80km/h, on a road with coarse surface. At each speed there is only 3dB difference between the models – so small you’re unlikely to notice it. However, while we measure noise at the very end of our harsh performance testing, the tyres are still relatively new and bigger differences may develop with increased wear.